<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子</title>
    <style>

        /*
         *   盒子模型
         *     border  margin  padding
         *        left/right  top/bottom
         *    外边距合并
        */

        .box{
            width: 100px;
            height: 100px;
            background-color: greenyellow;
            border: 1px solid red;
            margin-left: 200px;
            margin-top: 300px;
            padding: 3px;
        }


        .box1 {
            width: 100px;
            height: 100px;
            background-color: greenyellow;
            border: 1px solid red;
            margin-left: 200px;
            margin-bottom: 300px;
            padding: 3px;
        }

        .box2 {
            width: 100px;
            height: 100px;
            background-color: greenyellow;
            border: 1px solid red;
            margin-left: 200px;
            margin-top: 300px;
            padding: 3px;
        }

    </style>
</head>
<body>
<!--
   1. 长度和高度各100px
   2. 有背景色
   3. 出现的位置偏右偏下
-->
<div class="box1">
1
</div>
<div class="box2">
    1
</div>
</body>
</html>